Building boards, and more particularly, ceiling boards, have conventionally been made by wet laying processes and the boards resulting from such processes have had to be sawed in order to yield product having a required dimension. The use of saws is undesirable for a number of reasons. One reason is that a substantial amount of dust is created during the sawing process, thereby leading to fire hazards, and air pollution and health hazards. A second reason is that difficulty has often been encountered in maintaining saw registration so as to consistently provide product having exact dimensions and exact geometry (e.g., squareness).
Recently, U.S. Pat. No. 4,476,175 disclosed groove molded building boards which were prepared such that the use of saws could be avoided. Each board was provided with grooved lines of demarcation which permitted the removal of edge scrap, and also permitted the boards to be easily divided into individual board segments. However, no apparatus existed for the processing of such boards, and the separation of the scrap and the dividing of the boards into individual pieces had to be accomplished by hand.
A number of prior art references disclose apparatus for segmenting sheet materials. Certain of these references pertain to the segmenting of materials such as crackers; thus, U.S. Pat. No. 2,252,362 discloses apparatus whereby transversely weakened sheets of crackers can be conveyed through a station comprising a plurality of hold-down means such that, when the crackers pass over a fulcrum point, the crackers are fractured along the lines of weakness. U.S. Pat. No. 2,555,916 discloses a different type of apparatus comprising a conveyor band and a breaker band whereby the breaker and conveyor cooperate to fracture preweakened sheets of crackers along the lines of weakness.
Other references are also directed to the segmenting of building materials such as plaster board. Thus, U.S. Pat. No. 2,311,995 discloses a stacked breaking means by which plaster board may be passed over a series of rolls and flexed such that the board is fractured along preweakened lines. In addition, British Patent Specification No. 827,611 discloses apparatus by which a preweakened plaster board having a perforated top and bottom paper facing may be passed along the conveyor and over a hump, after which the leading edge of the board contacts a downwardly directed belt. The combination of the hump and the downwardly directed belt causes the board to flex and break along the lines of weakness.
Other references also relate to the segmenting of sheet materials. Thus, U.S. Pat. No. 3,517,869 discloses apparatus for breaking a prescored glass sheet whereby one end of a conveyor bearing the sheet is moved downwardly in a vertical direction to cause the glass to fracture along the score line. Also, West German Offenlegungsschrift No. 26 33 013 discloses apparatus by which a transversely weakened sheet material can be passed onto an upwardly directed conveyor and subsequently onto a horizontal conveyor, during which time the leading edge of the sheet is contacted by a downwardly directed belt. The combination of passing the sheet onto an inclined conveyor and then contacting it with a downwardly directed belt causes the bottom edge and then the upper edge of the transverse weakening lines to fracture, thereby segmenting the sheet.
Despite the existence of these references, no method was known in the art to separate a groove molded sheet-like building board material into individual panels while at the same time separating the sheet from the board scrap.
Accordingly, one objective of the present invention was to provide a simplified means of segmenting a groove molded building board while at the same time separating the board panels from the scrap.
Yet another objective of the present invention was to provide apparatus for segmenting a groove molded building board whereby the use of saws was avoided.
These and other advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follow.